Whole Exome Sequencing Studies the Association of Rare Variants in Key TGF-β1/SMAD Pathway Gene with Stress Urinary Incontinence Susceptibility

Background : Stress urinary incontinence (SUI) is a prevalent urological problem that is common among middle-aged and older women. Previous studies have shown that TGF-β1/SMAD pathway might play an important role in the pathogenesis of SUI. But the effect of polymorphisms in key genes in TGF-β1/SMAD pathway on the susceptibility to SUI remains unknown. Methods : Whole-exome sequencing (WES) was initially performed in 72 SUI women and 72 matched controls from Jiangxi Province, China. We analyzed rare variants in 7 key genes in TGF-β1/SMAD pathway that were predicted to be disease-causing and present exclusively in the cases. The potential pathogenicity of these candidate variants was assessed using the SIFT, Mutation Taster, and FATHMM prediction tools, and the detected variants were validated by Sanger sequencing. A validation cohort of 397 controls and 361 SUI patients was genotyped for these prioritized variants using both Massarray and KASP platforms. Results : WES revealed 111 variants in 7 key genes in TGFβ1/SMAD pathway among SUI cases. Following selection criteria (rare, predicted disease-causing, and absent in controls), four candidate missense variants were identified as potentially pathogenic for SUI: rs200111443 in the TGFBR2 gene, rs184408275 in the SMAD3 gene, rs1318674011 in the SMAD7 gene, and rs569594975 in the TGFB1 gene. Bioinformatic tools predicted the pathogenicity of these variants: SIFT and FATHMM classified rs200111443 as damaging, while FATHMM classified rs1318674011 as damaging. All four candidate variants were subsequently validated using Sanger sequencing. In the validation cohort (361 patients, 397 controls), none of the four candidate variants showed statistically significant associations with SUI susceptibility via Massarray/KASP genotyping (all p > 0.05). Notably, the rare missense variant (rs569594975) in TGFB1 gene was uniquely detected in SUI cases but absent in controls, suggesting a potential role in the pathogenesis of SUI which requires further investigation. Conclusions : Initial WES identified rare, potentially pathogenic missense variants in key TGFβ1/SMAD pathway genes exclusively among SUI cases. Subsequent large-scale validation using both Massarray and KASP genotyping assays in an independent cohort demonstrated no statistically significant association between the candidate variants (TGFBR2 rs200111443, SMAD3 rs184408275, SMAD7 rs1318674011, TGFB1 rs569594975) and SUI susceptibility. Notably, TGFB1 rs569594975 was uniquely detected in SUI patients, warranting functional investigation to clarify its biological relevance.